Angular momentum and galaxy formation
replacing galaxies in their cosmological environment

Corentin Cadiou
Astro Lunch Talk @ UCSB 2023

The effects of environment on halo properties

\(v/\sigma\) at fixed \(M_\star\)

Kraljic+18 [see also Laigle15, Song+21,…]

  • \( M_\mathrm{DM}(\text{node}) \) > \(M_\mathrm{DM}(\text{fil}) \) >\(M_\mathrm{DM}(\text{void})\), higher clustering
  • spins align with cosmic web ⇒ issue for weak lensing
  • \(v/\sigma(\mathrm{fil})>v/\sigma(\mathrm{void})\) ⇒ bias in galaxy formation
  • ….

The effects of environment on halo properties

\(v/\sigma\) at fixed \(M_\star\)

Kraljic+18 [see also Laigle15, Song+21,…]

  • \( M_\mathrm{DM}(\text{node}) \) > \(M_\mathrm{DM}(\text{fil}) \) >\(M_\mathrm{DM}(\text{void})\), higher clustering
  • spins align with cosmic web ⇒ issue for weak lensing
  • \(v/\sigma(\mathrm{fil})>v/\sigma(\mathrm{void})\) ⇒ bias in galaxy formation
  • ….

The effects of environment on halo properties

Isotropic effects

Kaiser bias, cluster vs. groups, ...

From theory: \(M\propto \int\mathrm{d}^3R\rho\)

Mass regulated

An-isotropic effects

Intrinsic alignment, formation of disks?

From theory: \(J \propto \int\mathrm{d}^3R \nabla \phi\)

Angular momentum regulated?

Angular momentum: bridging galaxies to cosmology?

Tillson+15

[also Dekel & Birboim 06, Danovich+15, Cadiou+21c]

Dekel&Birnboim 06

High-z:
most of mass + AM flow along filaments

Lower-zs:
intrinsic alignment problem

Tempel+13

Angular momentum: bridging galaxies to cosmology?

Tillson+15

[also Dekel & Birboim 06, Danovich+15, Cadiou+21c]

Dekel&Birnboim 06

High-z:
most of mass + AM flow along filaments

Lower-zs:
intrinsic alignment problem

Tempel+13

How do we detect these effects?

Large volumes

sample \(p(M_\star, M_\mathrm{DM},\mathbf{J}, d_\mathrm{fil}, \dots)\)

This talk

sample \(p(\mathbf{J}|M_\star, M_\mathrm{DM}, d_\mathrm{fil}, \dots)\)

Angular momentum: where are we?

Porciani+02

Adapted from Park+22

Rodriguez-Gomez+22

Predictions for \(j_\mathrm{DM}\) remain qualitative

\(j_\mathrm{DM}-j_\mathrm{\star}\)
strong detection of weak correlation

  1. Is \(j_\mathrm{DM}\) chaotic or our theory poor?
    Can we do better than statistical correlations?
  2. Do \(j_\mathrm{gal}\) retain memory of their environment?
    Can we spin a simulated galaxy up?
  3. What effect does anisotropic environment play in DM/gal formation?
    Can we simulate a galaxy in ≠environments?

Is \(j_\mathrm{DM}\) chaotic or our theory poor?

First controlled experiment of testing tidal torque theory for individual halos

 

CC+21a, arXiv: 2012.02201

Predicting angular momentum

\(z=0\)

\( z = 100\)

Predicting angular momentum

\(z=0\)

\( z = 100\)

\[\mathbf{L}_\mathrm{lin.} \propto \int\mathrm{d}^3q(\mathbf{q}-\bar{\mathbf{q}})\times \nabla\phi\]

Position w.r.t. center

Velocity

[White 84]

Note: vanishes at 1st order in a sphere

\[ \int_\Gamma \mathrm{d}^3{q}(\mathbf{q}-\mathbf{\bar{q}}) \times\nabla\phi  = \int_{\partial\Gamma}\phi(q)(\mathbf{q}-\mathbf{\bar{q}})\times\mathrm{d}\mathbf{S}\]

Note: the following is a (poor) approximation:

\[ \mathbf{L} \propto \epsilon_{ijk} T_{jl}I_{lk},\quad\text{with T the tidal tensor and I the inertia tensor}\]

Predicting angular momentum

\(z=0\)

\( z = 100\)

[Genetic modifications: Roth+16, see also Rey&Pontzen 18, Stopyra+20]

Predicting angular momentum

Time

Predicting angular momentum

Time

Time

Poor predictions

Good predictions

✅ AM of fixed DM regions can be predicted (so is not chaotic!)

Improve theory? Need good model of Lagrangian patch boundaries

Do \(j_\mathrm{gal}\) retain memory
of the environment?

First controlled experiment of angular momentum accretion on individual galaxies

 

CC+22, arXiv: 2206.11913

 

Main idea: stars are deeper in potential well so less sensitive to what happens at large scales

⇒ stellar Lagrangian patch should be more stable to perturbations

Baryon angular momentum

Full hydro simulations
(10Mh @ DiRAC):

  • Resolve disk height
    \(\Delta x = 35\ \mathrm{kpc}\)
  • \(z \geq 2\), \(M_\mathrm{200c} = 10^{12}\ \mathrm{M}_\odot\)
  • SF + AGN & SN feedback
  • Tracer particles
    CC+19
  • 3 galaxies, 5× scenario each

\( j_0 \times 0.66\)

\( j_0 \times 0.8\)

\( j_0 \times 1.2\)

\( j_0 \times 1.5\)

INPUT  \(z=200\)

OUTPUT
\(z=2\)

\( j_0 \times 0.66\)

\( j_0 \times 0.8\)

\( j_0 \times 1.2\)

\( j_0 \times 1.5\)

\( j_0 \times 0.66\)

\( j_0 \times 0.8\)

\( j_0 \times 1.2\)

\( j_0 \times 1.5\)

✅ Stellar AM driven by (past) tides with the cosmic web (which can be predicted)

No self-regulation of AM by feedback!

✅ Changes in baryon spAM \(\sim\) Changes in Halo spAM

Insight: matter in the outskirts (mostly gas & DM)
dominate spAM magnitude (& direction?)

Gas + stars spAM

Stars spAM

Halo spAM

Halo spAM

Effect(s) of anisotropic env DM/gal formation?

 Study same object, different environment.

 

CC+21, arXiv: 2107.03407

 

Cosmic web drives AM acquisition... what scales? what's affected?

What if the galaxy had formed here instead?

What if the galaxy had formed here instead?

or here?

The “splicing” technique

  1. Generate ICs
  2. Integrate (\(N\)-nody)
  3. Select region of interest
  4. Trace back to ICs
  5. “Splice”
  6. Integrate again

\(t\)

Splicing: equivalent of constraining field at all points in spliced region

The causal origin of DM halo concentration

\(M^{(1)}_{200\mathrm{c}}, c^{(1)}_\mathrm{NFW}, \dots\)

\(M^{(2)}_{200\mathrm{c}}, c^{(2)}_\mathrm{NFW}, \dots\)

\(M^{(\dots)}_{200\mathrm{c}}, c^{(\dots)}_\mathrm{NFW}, \dots\)

\(M^{(10)}_{200\mathrm{c}}, c^{(10)}_\mathrm{NFW}, \dots\)

Same halo in 10× different environments

Repeat experiment for 7 halos (70 realisations in total)

Same halo in 10× different environments

Repeat experiment for 7 halos (70 realisations in total)

\(M^{(1)}_{200\mathrm{c}}, c^{(1)}_\mathrm{NFW}, \dots\)

\(M^{(2)}_{200\mathrm{c}}, c^{(2)}_\mathrm{NFW}, \dots\)

\(M^{(\dots)}_{200\mathrm{c}}, c^{(\dots)}_\mathrm{NFW}, \dots\)

\(M^{(10)}_{200\mathrm{c}}, c^{(10)}_\mathrm{NFW}, \dots\)

The causal origin of DM halo concentration

Same halo in 10× different environments

Repeat experiment for 7 halos (70 realisations in total)

\(M^{(1)}_{200\mathrm{c}}, c^{(1)}_\mathrm{NFW}, \dots\)

\(M^{(2)}_{200\mathrm{c}}, c^{(2)}_\mathrm{NFW}, \dots\)

\(M^{(\dots)}_{200\mathrm{c}}, c^{(\dots)}_\mathrm{NFW}, \dots\)

\(M^{(10)}_{200\mathrm{c}}, c^{(10)}_\mathrm{NFW}, \dots\)

The causal origin of DM halo concentration

50% of population

Conclusion & outlook

Conclusion & outlook

  1. Is \(j_\mathrm{DM}\) chaotic or our theory poor?
    Poor theory! Good accuracy (few ~10%) achievable for individual halos in principle.
     
  2. Do \(j_\mathrm{gal}\) retain memory of their environment?
    Individual galaxies retain memory of env, can be controlled in simulations!
    Galaxies may be less stochastic than expected
     
  3. What effect does anisotropic environment play in DM formation?
    Changing env causes
    ⇒ ~15% change in mass
    ⇒ 50% of population scatter for concentration
    Very promising for intrinsic alignment studies!

The causal origin of DM halo concentration

$$\rho_\mathrm{DM}(r) = \frac{\rho_0}{\frac{r}{R_\mathrm{vir}/c} \left(1 + \frac{r}{R_\mathrm{vir}/c}\right)^2}$$

Wechsler+02

Origin of scatter at fixed \(M_\mathrm{vir}\)?

Predicting angular momentum

  • Angular momentum of individual regions can be predicted accurately.
  • AM of halos ⇒ requires boundaries of patch

\[\mathbf{L}_\mathrm{lin.} \propto \int\mathrm{d}^3q(\mathbf{q}-\bar{\mathbf{q}})\times \nabla\phi\]

[On patch boundaries: see Lucie-Smith+18]

Splicing in 1D

Splicing in 1D

Most likely* field \(f\) with

  • same value in spliced region (\(a\)),
  • as close as possible outside (\(b\))

Mathematically \(f\) is solution of:

\( f= a\) in \(\Gamma\)

minimizes \(\mathcal{Q} = (b-f)^\dagger\mathbf{C}^{-1}(b-f) \) outside \(\Gamma\)

Can we control baryonic
angular momentum?

Wechsler & Tinker 18

\({\color{red}M_\star} / M_\mathrm{h} \ll \Omega_b / \Omega_m \)
⇒ baryons & DM stem from different regions

Baryons more strongly bound
⇒ less prone to being ejected

Verify that

\[\xi_\mathrm{lin}(r) \sim \left\langle {\color{green}\underbrace{\delta(x=d)}_\mathrm{in}} {\color{purple} \underbrace{\delta(x=d+r)}_\mathrm{out}}\right\rangle \]

is the same in spliced / ref simulation.

Verify that

\[\xi_\mathrm{lin}(r) \sim \left\langle {\color{green}\underbrace{\delta(x=d)}_\mathrm{in}} {\color{purple} \underbrace{\delta(x=d+r)}_\mathrm{out}}\right\rangle \]

is the same in spliced / ref simulation.

Verify that

\[\xi_\mathrm{lin}(r) \sim \left\langle {\color{green}\underbrace{\delta(x=d)}_\mathrm{in}} {\color{purple} \underbrace{\delta(x=d+r)}_\mathrm{out}}\right\rangle \]

is the same in spliced / ref simulation.

Temporary conclusions

  • angular momentum is predictable

     

  • boundary of halos in the ICs is a hard problem
    ⇒ limits practicality of predictions (for now)

     

  • baryons appear to be simpler!
    ⇒ good news for weak lensing predictions
    ⇒ key to understand morphology

Galaxy formation in cosmology: the role of the environment

Environmental effects:

  • source of “pollution” in weak lensing surveys
    ⇒ intrinsic alignment
     
  • extra parameters in semi-analytical models
    ⇒ galaxy-halo correlation

+

\( R_{1/2} \)

\( l_0 \times 1.2\)

\( l_0 \times 1.5\)

\( l_0 \times 0.66\)

\( l_0 \times 0.8\)

\( l_0 \times 0.66\)

\( l_0 \times 0.8\)

\( l_0 \times 1.2\)

\( l_0 \times 1.5\)

\( l_0 \times 1.2\)

\( l_0 \times 1.5\)

\( l_0 \times 0.66\)

\( l_0 \times 0.8\)

\( l_0 \times 1.2\)

\( l_0 \times 1.5\)

\( l_0 \times 0.66\)

\( l_0 \times 0.8\)

  • AM of baryons originates from initial conditions…
  • can be controlled…
  • and regulate galaxy morphology
  • Negligible AGN/SN global self-regulation

Galaxy formation

[L. Cortese; SDSS.]

[Dubois+16]

AGN         no AGN

Origin of morphological diversity at fixed mass?

[L. Cortese; SDSS.]

[Dubois+16]

AGN         no AGN

Origin of morphological diversity at fixed mass?

How to explain environmental effects?

[Kraljic+ in prep]

Galaxy formation

[Danovich+15]

The origin of high \(z\) angular momentum

[Danovich+15]

I. Torque with cosmic web

The origin of high \(z\) angular momentum

[Danovich+15]

I. Torque with cosmic web

II. Transport at constant AM

The origin of high \(z\) angular momentum

[Danovich+15]

I. Torque with cosmic web

II. Transport at constant AM

III. Torque down in inner halo

The origin of high \(z\) angular momentum

[Danovich+15]

I. Torque with cosmic web

II. Transport at constant AM

III. Torque down in inner halo

IV. Mixing in inner disk & bulge

The origin of high \(z\) angular momentum

The origin of high \(z\) angular momentum

[Danovich+15]

IV. Mixing in inner disk & bulge

Fraction that ends up in disk vs. IGM?

Influence of galactic physics?

III. Torque down in inner halo

Origin of torque down (pressure or gravity)?

Loss of link with cosmic AM?

II. Transport at constant AM

Same evolution in cold/hot accretion modes?

I. Torque with cosmic web

Predict pre-accretion AM?

Alignment with environment?

The origin of high \(z\) angular momentum

[Danovich+15]

IV. Mixing in inner disk & bulge

Fraction that ends up in disk vs. IGM?

Influence of galactic physics?

III. Torque down in inner halo

Origin of torque down (pressure or gravity)?

Loss of link with cosmic AM?

See Cadiou+21c

II. Transport at constant AM

Same evolution in cold/hot accretion modes?

I. Torque with cosmic web

Predict pre-accretion AM?

Alignment with environment?

The origin of high \(z\) angular momentum

[Danovich+15]

IV. Mixing in inner disk & bulge

Fraction that ends up in disk vs. IGM?

Influence of galactic physics?

III. Torque down in inner halo

Origin of torque down (pressure or gravity)?

Loss of link with cosmic AM?

II. Transport at constant AM

Same evolution in cold/hot accretion modes?

I. Torque with cosmic web

Predict pre-accretion AM?

Alignment with environment?